JP2002132054A - Image forming device, image forming method and transfer device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To suppress irregularities in the velocity of a transfer/carrying belt, and to improve a transfer/carry belt cleaning performance. SOLUTION: The device is provided with photoreceptors 11Y, 11M, 11C and 11K for forming toner images, constituted of electrified toner having a prescribed polarity, the transfer/carry belt 60 constituted with the surface being moved along an endless path, including a transfer nip part facing in contact with each photoreceptor 11, and for carrying and transferring a transfer paper P to the transfer nip part, a cleaning roller 66 for cleaning the surface of the transfer/carry belt 60 at a cleaning nip part facing in contact with the surface of the transfer/carry belt 60, and a cleaning bias power source 66a for applying cleaning bias on the cleaning roller 66, and a relative velocity difference is made between the linear velocity of the transfer/carry belt 60 and that of the cleaning roller 66 at the cleaning nip part.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an image forming apparatus such as a copying machine, a printer and a facsimile, an image forming method, and the like.
And a transfer device used in the image forming apparatus.

[0002]

2. Description of the Related Art Conventionally, the surface has moved along an endless path including an image carrier on which a toner image formed of a charged toner having a predetermined polarity is formed, and a transfer nip portion in contact with and opposed to the image carrier. A transfer conveyance belt that carries and conveys the transfer material to the nip portion; a cleaning member that cleans the surface of the transfer conveyance belt at a cleaning nip portion that is in contact with and opposes the surface of the transfer conveyance belt; 2. Description of the Related Art An image forming apparatus including a cleaning electric field forming unit that forms a cleaning electric field that moves the charged toner having the predetermined polarity to the cleaning member side between the transfer conveying belt and the transfer conveying belt is known.

FIG. 9 is a schematic diagram showing an example of the image forming apparatus. This image forming apparatus is provided with the photoconductor 11 as the image carrier, the transfer and conveyance belt 60, and the cleaning roller 66 as the cleaning member. In this example, a cleaning nip in which the transfer conveyance belt 60 and the cleaning roller 66 come into contact with each other is applied by applying a bias having a polarity opposite to the charging polarity of the toner to the cleaning roller 66 made of a conductive member from the cleaning bias power source 66a. A cleaning electric field is formed in the section so that the toner moves to the cleaning roller 66 side. Also,
A pair of registration rollers for nipping and transporting the transfer paper P to supply the transfer paper P onto the transfer transport belt 60, and a fixing unit 7 including a fixing roller and a pressure roller for fixing the toner image transferred onto the transfer paper P are also provided. Is provided.

In the illustrated image forming apparatus, a toner image is formed on the photoconductor 11 by toner image forming means (not shown) disposed around the photoconductor 11. The transfer paper P sent at a predetermined timing by the registration roller pair 5 is
When passing between the electrostatic attraction roller 65 and the support roller 61, the toner is electrostatically attracted onto the transfer / transport belt 60, and
The sheet is conveyed to a transfer nip portion which is in contact with and opposed to the sheet. Then, the toner image on the photoconductor 11 is transferred onto the transfer paper P at the transfer nip portion. The transfer paper P on which the toner image has been transferred is separated from the transfer conveyance belt 60, and the toner image is fixed by the fixing unit 7. On the other hand, in the transfer conveyance belt 60 after the transfer paper P is separated, the toner adhered to the belt surface is cleaned at the cleaning nip portion. Specifically, due to the cleaning electric field, the charged toner having a predetermined polarity attached to the surface of the transfer conveyance belt 60 is transferred to the cleaning roller 71 side by electrostatic force, and the toner is removed from the surface. Since the electrostatic force is used as described above, for example, when a cleaning member such as a cleaning blade that cleans only with a mechanical force such as a mechanical rubbing force or a toner damping force is used, a transfer member is used. This is advantageous in that there is little mechanical damage to the member surface and the lining member.

[0005]

By the way, in the image forming apparatus shown in the drawing, in order to suppress the speed unevenness of the transfer / conveyance belt 60, the linear velocity of the transfer / conveyance belt 60, the photoconductor 11 and the cleaning roller 71 are controlled. It has been considered preferable to set the linear velocity to be constant. However, even in such a setting, a load may be applied to the transfer conveyance belt 60 as the transfer paper P is supplied to and separated from the transfer conveyance belt 60, and the speed of the transfer conveyance belt 60 may be uneven. Specifically, for example, at the moment when the leading end of the transfer paper P supplied from the registration roller pair 5 reaches the transfer conveyance belt 60, or at the moment when the rear end of the transfer paper P passes through the holding portion of the registration roller pair 5, Thus, a load is applied to the transfer / conveyance belt, and the speed of the transfer / conveyance belt 60 becomes uneven. Also, at the moment when the leading end of the transfer paper P reaches the roller holding portion of the fixing unit 7 or at the moment when the rear end of the transfer paper P separates from the transfer / transport belt, a load is generated on the transfer / transport belt, and 60 speed unevenness occurs. Hereinafter, the occurrence of such speed unevenness will be described more specifically.

First, a description will be given of the speed unevenness of the transfer / transport belt 60 that occurs with the supply of the transfer paper P from the registration roller pair 5 to the transfer / transport belt 60. For example, if the linear velocity of the pair of registration rollers 5 is set to be equal to the linear velocity of the transfer conveyance belt 60, the linear velocity of the pair of registration rollers 5 may vary depending on the thickness of the transfer paper P to be used and variations in the accuracy of the components of the pair of fixing rollers. However, there is a case where the linear velocity of the transfer conveyance belt 60 becomes lower. In such a case, at the moment when the leading end of the transfer paper P reaches the transfer conveyance belt 60, a load is generated on the transfer conveyance belt 60 due to the speed difference between the two, and the speed of the transfer conveyance belt 60 fluctuates. At the moment when the rear end of the transfer paper P passes through the holding portion of the registration roller pair 5, a load that pulls the transfer conveyance belt 60 by the transfer paper P in the direction opposite to the belt surface moving direction is released. A large speed fluctuation occurs in the transfer conveyance belt 60.

As a countermeasure to reduce the speed fluctuation of the transfer conveyance belt 60 due to the trailing edge of the transfer paper P, generally, the linear speed of the pair of registration rollers 5 is set to be higher than the linear speed of the transfer conveyance belt 60. It is valid. When the linear velocity of the pair of registration rollers 5 is set to be always higher than the linear velocity of the transfer conveyance belt 60, as shown in FIG. The transfer paper P ′ is bent in an arch shape between the registration roller holding portion and the transfer / transport belt 60 due to the stiffness of the transfer paper itself, and the transfer / transport belt 60 by the transfer paper is moved in a direction opposite to the belt surface moving direction. No pulling load occurs. Therefore, the speed unevenness of the transfer conveyance belt 60 due to the trailing edge of the transfer paper can be reduced. However, even when the linear speed of the registration roller pair 5 is set to be always higher than the linear speed of the transfer conveyance belt 60, it is possible to completely eliminate the speed unevenness of the transfer conveyance belt 60 due to the trailing edge of the transfer paper being omitted. Can not. Also, the transfer paper P
The speed unevenness of the transfer conveyance belt 60 due to the speed difference between the two at the moment when the tip of '′ reaches the transfer conveyance belt 60 cannot be solved.

Next, a description will be given of the speed unevenness of the transfer / transport belt 60 caused by the separation of the transfer sheet P from the transfer / transport belt 60 toward the fixing unit 7. For example,
When the linear velocity of the fixing roller and the pressure roller of the fixing unit 7 is set to be equal to the linear velocity of the transfer conveyance belt 60, the linear velocity of the fixing roller and the pressure roller becomes larger than the linear velocity of the transfer conveyance belt 60. In some cases. In such a case, at the moment when the rear end of the transfer paper P separates from the transfer / conveyance belt 60, the load that pulls the transfer / conveyance belt 60 by the transfer paper P in the belt surface movement direction is released. A large speed fluctuation occurs in the belt 60.

As a countermeasure for reducing the speed unevenness of the transfer conveyance belt 60 due to the separation of the transfer paper P, generally, the linear speed of the fixing roller and the pressure roller is made lower than the linear speed of the transfer conveyance belt 60. Is valid. According to this, in the same manner as described for the registration roller pair 5, the transfer paper P 'is bent in an arch shape between the roller holding portion of the fixing unit 7 and the transfer conveyance belt 60 due to the stiffness of the transfer paper itself. (See FIG. 9), and there is no load that pulls the transfer / transport belt 60 of the transfer paper in the belt surface movement direction. Accordingly, the speed unevenness of the transfer conveyance belt 60 due to the separation of the transfer paper P can be reduced. However, if the linear velocity of the fixing roller and the pressure roller is set to be always lower than the linear velocity of the transfer conveyance belt 60, the moment the rear end of the transfer paper P ′ separates from the transfer conveyance belt 60, A load occurs that pushes the transfer conveyance belt 60 by the transfer paper P ′ in the direction opposite to the belt surface movement direction. Further, regardless of the magnitude relationship between the linear velocity of the fixing roller and the pressure roller and the linear velocity of the transfer conveyance belt 60, the transfer conveyance is caused by the impact when the leading edge of the transfer paper abuts the holding portion of the fixing roller and the pressure roller. The belt 60 has uneven speed.

As described above, as the transfer paper P is supplied to and separated from the transfer conveyance belt 60, the transfer conveyance belt 60
When the speed unevenness occurs, pitch unevenness occurs on the image, and the image quality deteriorates. In particular, it has a plurality of photoconductors on which toner images of different colors are formed, and moves the transfer conveyance belt along an endless path including a plurality of transfer nip portions facing each of the plurality of photoconductors. In an image forming apparatus that forms a color image by superimposing and transferring a toner image onto transfer paper, a color shift occurs.

Here, as a method of reducing the speed unevenness of the transfer conveyance belt 60, for example, at least one of the support rollers 61 and 62 in FIG. 9 is used as a tension roller, and the transfer roller 6
A method of increasing the tension between the support rollers 61 and 62 of the transfer belt 60, that is, the transfer paper transfer area of the transfer transfer belt 60 is considered. If the transfer paper conveyance area of the transfer conveyance belt 60 is strengthened in this way, the transfer conveyance belt 60 is less affected by the supply and separation of the transfer paper, and the speed unevenness is less likely to occur. Therefore, it is possible to reduce the pitch unevenness and the color shift on the image due to the speed unevenness of the transfer conveyance belt. However, there is a limit in this method, too.
The speed unevenness of 0 could not be completely suppressed.

SUMMARY OF THE INVENTION The present invention has been made in consideration of the above problems, and has as its object to reduce the unevenness of the speed of the transfer conveyance belt and improve the cleaning performance of the transfer conveyance belt. An apparatus, an image forming method, and a transfer device are provided.

[0013]

According to a first aspect of the present invention, there is provided an image bearing member on which a toner image formed of a charged toner having a predetermined polarity is formed, and the image bearing member is in contact with and opposed to the image bearing member. A transfer conveyance belt whose surface moves along an endless path including a transfer nip portion and carries and transfers a transfer material to the transfer nip portion; An image forming apparatus comprising: a cleaning member for cleaning a surface of a belt; and a cleaning electric field forming means for forming a cleaning electric field for moving the charged toner having the predetermined polarity to the cleaning member side in the cleaning nip portion. Having a relative speed difference between the linear speed of the transfer conveyance belt and the linear speed of the cleaning member in the cleaning nip portion. It is an butterfly.

In this image forming apparatus, the slack of the transfer conveyance belt in the transfer material conveyance area is reduced by a relative speed difference between the linear speed of the transfer conveyance belt in the cleaning section and the linear speed of the cleaning member. The area is always kept taut. In order to maintain the transfer material conveying area in a stretched state as described above, for example, as described later in claim 2, a maximum driving force is applied to the transfer conveying belt among a plurality of support rollers for supporting the transfer conveying belt. The supporting roller to be applied is disposed downstream of the transfer nip portion in the surface movement direction of the transfer conveyance belt, and the cleaning member is disposed further downstream than the supporting roller that applies the maximum driving force. The linear velocity of the transfer conveyance belt is set to be higher than the surface movement of the cleaning member, and as described later in claim 5, among a plurality of support rollers for supporting the transfer conveyance belt. A support roller for applying a maximum driving force to the transfer conveyance belt is disposed upstream of the transfer nip portion in the surface movement direction of the transfer conveyance belt, and The cleaning member is disposed further upstream than the support roller that applies the maximum driving force, and the linear velocity of the cleaning member is set to be higher than the linear velocity of the transfer conveyance belt. I do. By keeping the transfer material transporting area of the transfer transport belt stretched at all times, the transfer material supply and separation are less affected by the transfer material, and the load on the transfer transport belt due to the supply and separation can be reduced. As a result, speed unevenness of the transfer conveyance belt can be suppressed. Further, a shear force is applied to the toner between the transfer conveyance belt and the cleaning member by a relative speed difference between the linear speed of the transfer conveyance belt and the linear speed of the cleaning member in the cleaning nip portion. With this shear force,
A part of the toner adhered to the surface of the transfer conveyance belt is mechanically peeled off, and the charged toner adhered to the surface of the transfer conveyance belt is easily cleaned by the cleaning electric field. Thereby, the cleaning performance of the transfer conveyance belt can be improved.

According to a second aspect of the present invention, in the image forming apparatus according to the first aspect, a support roller that applies a maximum driving force to the transfer transport belt among the plurality of support rollers that support the transfer transport belt is connected to the transfer roller. The cleaning member is disposed downstream of the nip portion in the surface movement direction of the transfer conveyance belt, and the cleaning member is disposed further downstream of the support roller that applies the maximum driving force. The speed is set to be higher than the linear speed of the cleaning member.

In this image forming apparatus, a supporting roller for applying a maximum driving force to the transfer / conveying belt is disposed downstream of the transfer nip in the surface moving direction of the transfer / conveying belt, and a cleaning member is provided. The transfer nip portion is disposed further downstream than the support roller that applies the maximum driving force, and the linear speed of the transfer conveyance belt is set to be higher than the linear speed of the cleaning member. A tension in the direction opposite to the belt surface moving direction is generated in the transfer conveyance belt between the cleaning unit and the support roller. This tension reduces the slack of the transfer conveyance belt between the cleaning section including the transfer nip section and the support roller, and keeps this section always stretched.

According to a third aspect of the present invention, in the image forming apparatus of the second aspect, the linear speed of the transfer conveyance belt in the transfer section is set to be higher than the linear speed of the image carrier. It is assumed that.

In the image forming apparatus of the second aspect,
When the linear velocity of the image carrier and the linear velocity of the transfer conveyance belt are set to a constant velocity, the linear velocity of the image carrier at the transfer nip is larger than the linear velocity of the transfer conveyance belt due to, for example, eccentricity of the support roller. May be. In such a case,
Due to the rotation of the image carrier, a force for pushing the transfer conveyance belt in the surface movement direction of the transfer conveyance belt is generated, and the transfer conveyance belt is moved between the transfer nip portion and the support roller that applies the maximum driving force. There is a risk of loosening. In the image forming apparatus according to the third aspect, since the linear speed of the transfer conveyance belt in the transfer unit is set to be higher than the linear speed of the image carrier, the transfer nip portion and the maximum driving force are set to be equal to each other. The transfer conveyance belt is prevented from being loosened between the transfer roller and the support roller to be applied, and this portion is always maintained in a stretched state.

According to a fourth aspect of the present invention, in the image forming apparatus of the second aspect, the linear speed of the image carrier in the transfer nip portion is set to be higher than the linear speed of the transfer / transport belt. The difference in relative speed between the cleaning member and the transfer / conveying belt is set to be larger than the difference in relative speed between the image carrier and the transfer / conveying belt.

In this image forming apparatus, the linear velocity of the image carrier at the transfer nip is set to be higher than the linear velocity of the transfer / conveying belt. In such a setting, as described in claim 3, a force for pushing the transfer conveyance belt in the surface movement direction of the transfer conveyance belt is generated, and the transfer roller and the support roller for applying the maximum driving force are provided. Between the transfer belt and the transfer conveyance belt. In this image forming apparatus, in addition to the above settings, the relative speed difference between the cleaning member and the transfer conveyance belt is set to be larger than the relative speed difference between the image carrier and the transfer conveyance belt. Therefore, the tension in the direction opposite to the belt surface movement direction acting on the transfer conveyance belt between the cleaning unit and the transfer nip portion on the upstream side of the transfer nip portion in the surface movement direction of the transfer conveyance belt is higher than that of the transfer nip. The force acting on the transfer conveyance belt between the unit and the support roller that gives the maximum driving force pushes out the transfer conveyance belt. This suppresses the slack of the transfer conveyance belt between the transfer nip portion and the support roller that applies the maximum driving force, and maintains this portion in a stretched state at all times.

According to a fifth aspect of the present invention, in the image forming apparatus of the first aspect, a support roller for applying a maximum driving force to the transfer conveyance belt among the plurality of support rollers for supporting the transfer conveyance belt is provided. The cleaning member is disposed upstream of the nip portion in the surface movement direction of the transfer conveyance belt, and the cleaning member is disposed further upstream of the support roller that applies the maximum driving force. The speed is set to be higher than the linear speed of the transfer conveyance belt.

In this image forming apparatus, a support roller for applying a maximum driving force to the transfer / conveying belt is disposed upstream of the transfer nip in the surface moving direction of the transfer / conveying belt, and a cleaning member is provided. Since the cleaning member is disposed further upstream than the supporting roller that applies the maximum driving force, and the linear velocity of the cleaning member is set to be higher than the linear velocity of the transfer conveyance belt, the transfer nip portion A tension in the belt surface moving direction is generated in the transfer / conveying belt between the support roller and the cleaning nip portion. This tension reduces the slack of the transfer conveyance belt between the support roller including the transfer nip and the cleaning nip, and keeps this portion always in a tensioned state.

According to a sixth aspect of the present invention, in the image forming apparatus of the fifth aspect, the linear speed of the image carrier in the transfer nip portion is set to be higher than the linear speed of the transfer / transport belt. It is a feature.

In the image forming apparatus according to the fifth aspect,
When the linear velocity of the image carrier and the linear velocity of the transfer / transport belt are set to be equal, the linear velocity of the transfer / transport belt becomes higher than the linear velocity of the image carrier, as described in the third aspect. There are cases. In such a case, the transfer conveyance belt may be loosened between the support roller that applies the maximum driving force and the transfer nip. In the image forming apparatus according to the present invention, since the linear velocity of the image carrier in the transfer nip portion is set to be higher than the linear velocity of the transfer / conveying belt, the supporting roller for applying the maximum driving force is provided. The slack of the transfer conveyance belt between the transfer portion and the transfer portion is reduced, and this portion is always maintained in a stretched state.

According to a seventh aspect of the present invention, in the image forming apparatus of the fifth aspect, the linear speed of the transfer / conveying belt at the transfer nip is set to be higher than the linear speed of the image carrier. The difference in relative speed between the cleaning member and the transfer / conveying belt is set to be larger than the difference in relative speed between the image carrier and the transfer / conveying belt.

In this image forming apparatus, the linear speed of the transfer / transport belt at the transfer nip is set to be higher than the linear speed of the image carrier. In such a setting, as described in claim 6, the transfer conveyance belt may be loosened between the support roller that applies the maximum driving force and the transfer nip portion. In this image forming apparatus, in addition to the above settings, the relative speed difference between the cleaning member and the transfer conveyance belt is set to be larger than the relative speed difference between the image carrier and the transfer conveyance belt. Therefore, the maximum drive is performed by the tension in the belt surface movement direction acting on the transfer conveyance belt between the transfer nip portion and the cleaning nip portion downstream of the transfer nip portion in the surface movement direction of the transfer conveyance belt. The transfer conveyance belt between the support roller for applying the force and the transfer nip is hardly loosened. Thereby, the slack of the transfer conveyance belt between the support roller for applying the maximum driving force and the transfer nip portion is reduced, and this portion is always maintained in a stretched state.

According to an eighth aspect of the present invention, in the image forming apparatus according to any one of the first to seventh aspects, the linear velocity of the cleaning member is 98% or less of the linear velocity of the transfer / transport belt.
Alternatively, it is characterized by being at least 102%.

In this image forming apparatus, the linear velocity difference between the cleaning member and the transfer / conveying belt is set to a predetermined range or more, so that the linear velocity difference is set smaller than this range. As a result, a sufficient tension can be generated in the transfer and conveyance belt, and a sufficient shearing force can be applied to the toner adhered to the surface of the transfer and conveyance belt.

According to a ninth aspect of the present invention, in the image forming apparatus of any one of the first to eighth aspects, a plurality of the image carriers are provided, and the plurality of image carriers are formed with toner images of different colors from each other. The transfer conveyance belt is moved along an endless path including a plurality of transfer nip portions facing each of the plurality of image carriers, and each toner image is transferred by being overlapped on a transfer material. It is characterized by forming an image.

In this image forming apparatus, a transfer material is carried and transported by a transfer / transport belt, and the transfer material is opposed to a plurality of transfer nip portions which are in contact with and face a plurality of image carriers, respectively. The toner image on the carrier is superimposed on the transfer material and transferred. Then, the speed unevenness of the transfer / conveying belt can be suppressed in the same manner as described above in claim 1, the color shift of the superimposed image caused by the speed unevenness can be suppressed, and the image quality is improved. be able to.

According to a tenth aspect of the present invention, a step of forming a toner image composed of a charged toner having a predetermined polarity on an image carrier, and moving the surface along an endless path including a transfer nip portion in contact with the image carrier. Transferring the toner image on the image carrier to the transfer material by carrying and transferring the transfer material with the transfer / transport belt, and applying the transfer material to the cleaning unit where the transfer / transport belt and the cleaning member come into contact with each other. A cleaning electric field for moving the charged toner of a predetermined polarity to the cleaning member side, and a cleaning step of cleaning the transfer conveyance belt after the transfer. The linear velocity of the cleaning member has a relative velocity difference between the linear velocity and the linear velocity of the cleaning member.

According to this image forming method, by the same operation as that of the first aspect, it is possible to suppress the speed unevenness of the transfer / conveyance belt and improve the cleaning performance of the transfer / conveyance belt.

According to an eleventh aspect of the present invention, in the image forming method of the tenth aspect, of the plurality of support rollers for supporting the transfer / conveying belt, the downstream side of the transfer nip portion in the surface moving direction of the transfer / conveying belt. With a support roller provided upstream of the cleaning nip portion in the surface movement direction of the transfer conveyance belt, a maximum driving force is applied to the transfer conveyance belt, and the linear velocity of the transfer conveyance belt is
The linear velocity of the cleaning member may be higher than the linear velocity.

In this image forming method, the slack of the transfer conveyance belt between the cleaning section including the transfer nip section and the support roller is reduced by the same operation as in claim 2, and this section is always stretched. Maintained.

According to a twelfth aspect of the present invention, in the image forming method of the tenth aspect, of the plurality of support rollers for supporting the transfer / conveyance belt, the upstream side of the transfer nip portion in the surface movement direction of the transfer / conveyance belt. With a support roller provided downstream of the cleaning nip portion, a maximum driving force is applied to the transfer / transport belt, and the linear velocity of the cleaning member is set to be greater than the linear velocity of the transfer / transport belt. It is characterized by doing.

In this image forming method, the slack of the transfer conveyance belt between the supporting roller including the transfer nip and the cleaning nip is reduced by the same operation as in the fifth aspect, and this portion is always reduced. Keep stretched.

According to a thirteenth aspect of the present invention, there is provided a transfer / conveying belt whose surface moves along an endless path including a transfer nip portion which comes into contact with and faces the image carrier, and which carries and conveys a transfer material on the transfer nip portion; A cleaning member that cleans the surface of the transfer conveyance belt at a cleaning nip portion that is in contact with and opposes the surface of the transfer conveyance belt; and a cleaning member that moves the charged toner having the predetermined polarity to the cleaning member side at the cleaning nip portion. A transfer device provided with a cleaning electric field forming means for forming an electric field, wherein a relative speed difference is provided between a linear speed of the transfer conveyance belt and a linear speed of the cleaning member in the cleaning nip portion. Things.

According to this transfer device, by the same operation as in the first aspect, it is possible to suppress unevenness in the speed of the transfer / transport belt and improve the cleaning performance of the transfer / transport belt.

According to a fourteenth aspect of the present invention, in the transfer device according to the thirteenth aspect, a support roller that applies a maximum driving force to the transfer transport belt among the plurality of support rollers that support the transfer transport belt is connected to the transfer nip. And the cleaning member is disposed further downstream than the support roller that applies the maximum driving force, and the linear velocity of the transfer conveyance belt is adjusted. Is set to be higher than the linear velocity of the cleaning member.

In this transfer apparatus, the slack of the transfer conveyance belt between the cleaning section including the transfer nip section and the support roller is reduced by the same operation as in claim 2, and this section is always stretched. Keep in state.

According to a fifteenth aspect of the present invention, in the transfer device according to the thirteenth aspect, the transfer nip comprises a support roller for applying a maximum driving force to the transfer transport belt among the plurality of support rollers for supporting the transfer transport belt. And the cleaning member is disposed further upstream than the support roller that applies the maximum driving force, and the linear velocity of the cleaning member is Is set to be higher than the linear speed of the transfer / conveying belt.

In this transfer device, the slack of the transfer conveyance belt between the support roller including the transfer nip and the cleaning nip is reduced by the same operation as in the fifth aspect, and this portion is always stretched. Maintained.

[0043]

[Embodiment 1] Hereinafter, the present invention will be described.
An embodiment applied to an electrophotographic color laser printer (hereinafter, referred to as “laser printer”) as an image forming apparatus will be described. FIG. 2 is a schematic configuration diagram of the laser printer according to the present embodiment. This laser printer is
Four sets of toner image forming units 1Y, 1M, 1C, and 1K for forming images of each color of yellow (Y), magenta (M), cyan (C), and black (K) ,
M, C, and K are yellow, magenta, cyan,
Indicating that the member is for black). These are arranged in the above-described order from the upstream side along the moving direction of the transfer paper as the transfer material (the direction of arrow A in the figure). Each of the toner image forming units 1Y, 1M, 1C, and 1K is a photosensitive drum 11Y, 11M, 11C, 11 as an image carrier.
A photoconductor unit having K and a developing unit are provided. The rotation axes of the photoconductor drums in each photoconductor unit are parallel to each other, and are set at positions spaced at a predetermined pitch in the transfer paper moving direction.

The laser printer further includes a light source, a polygon mirror, an f-θ lens, a reflection mirror, and the like in addition to the toner image forming units 1Y, 1M, 1C, and 1K. 11Y, 11M, 11C,
An optical writing unit 2 for irradiating the surface of the 11K with a laser beam while scanning it is provided. Paper cassettes 3, 4,
A transfer unit 6 is provided as a transfer device having a pair of registration rollers 5 and a transfer conveyance belt 60 that carries the transfer paper and conveys the transfer paper so as to pass through the transfer position of each toner image forming unit. Further, a fixing unit 7 of a belt fixing type, a paper discharge tray 8, a manual feed tray (not shown), a toner supply container, a waste toner bottle, a duplex / reversing unit, a power supply unit, and the like are also provided.

The dashed line in FIG. 2 indicates the transfer path of the transfer paper. The transfer paper fed from the paper feed cassettes 3 and 4 is transported by transport rollers while being guided by a transport guide (not shown), and is transported to a temporary stop position where the registration roller pair 5 is provided. The transfer paper supplied at a predetermined timing by the pair of registration rollers 5 is carried by a transfer conveyance belt 60, and is conveyed so as to pass through a transfer nip portion where each photoconductor drum 11 and the transfer conveyance belt 60 are in contact with and opposed to each other. You. Each toner image forming unit 1Y, 1M, 1C, 1K
The transfer paper on which the toner image is transferred and the color image is formed is separated from the transfer / conveyance belt 60 and the fixing unit 7
After the toner image is fixed, the sheet is discharged onto the sheet discharge tray 8.

FIG. 3 shows the toner image forming sections 1Y, 1M,
FIG. 3 is an enlarged view showing a schematic configuration of a yellow toner image forming unit 1Y of 1C and 1K. Other toner image forming units 1M,
1C and 1K have the same configuration, respectively, and thus description thereof is omitted. In FIG. 3, the toner image forming unit 1Y includes the photoconductor unit 10Y and the developing unit 20Y as described above. Photoconductor unit 10
Y denotes a photosensitive drum 11Y, a brush roller 12Y for applying a lubricant to the photosensitive drum surface, a swingable counter blade 13Y for cleaning the photosensitive drum surface, and a uniform charging of the photosensitive drum surface. And a non-contact type charging roller 15Y. As the photoconductor drum of each photoconductor unit, a photoconductor drum having an organic photoconductor (OPC) layer on the surface was used. The developing unit 20Y uses a two-component developer including a magnetic carrier and a negatively charged toner having a desired charge polarity (hereinafter, referred to as a normal polarity). Then, a developing roller 22Y as a developer carrying member, which is disposed so as to be partially exposed from an opening on the photosensitive drum side of the developing case 21Y, conveying screws 23Y and 24Y, a developing doctor 25Y, a toner density sensor (T sensor) ) 26Y, a powder pump 27Y, and the like. The developer accommodated in the developing case 21Y is agitated and transported by the transporting screws 23Y and 24Y and is charged by friction. Then, a part of the developer is
After being carried on the surface of Y and having its thickness regulated by the developing doctor 25Y, it is conveyed to a developing position facing the photosensitive drum 11Y. At the developing position, the electrostatic latent image on the photosensitive drum 11Y is developed by the toner in the developer on the developing roller. The toner concentration of the developer in the developing case 21Y is detected by the toner concentration sensor 26Y, and toner is supplied by a powder pump 27Y as needed.

In the toner image forming section having the above structure, the light is applied to the surface of the photosensitive drum 11Y, which is uniformly charged to minus 700 volts having the same polarity as the normal polarity of the toner by the charging roller 15Y to which the AC voltage is applied. When the laser beam modulated and deflected by the writing unit 2 is irradiated while being scanned, an electrostatic latent image is formed on the surface of the photosensitive drum 11Y. The electrostatic latent image on the photoreceptor drum 11Y is reversely developed using the negatively charged toner in the developing unit 20Y to be a yellow toner image. Transfer conveyance belt 60
At the transfer position Pt where the upper transfer paper P passes, the toner image on the photosensitive drum 11Y is transferred to the transfer paper P. The surface of the photoconductor drum 11Y after the transfer of the toner image is coated with a predetermined amount of lubricant by the brush roller 12Y, and then cleaned by the counter blade 13Y to prepare for the formation of the next electrostatic latent image.

FIG. 1 is a schematic structural view of the transfer unit 6. The transfer conveyance belt 60 carries and conveys the transfer paper P, and the photosensitive pair drums 11Y, 11Y of each toner image forming unit.
The transfer paper P is wound around four grounded support rollers 61 to 64 so that the transfer paper P faces each photosensitive drum 11 at each transfer nip portion that comes into contact with and faces M, 11C, and 11K. The transfer conveyance belt 60 used in the transfer unit 6
Is, for example, PVDF (polyvinylidene fluoride).

An electrostatic attraction roller 65 is opposed to the entrance roller 61 of the support rollers 61 to 64 on the upstream side in the transfer paper moving direction. This electrostatic attraction roller 65
Is obtained by forming a conductive foamed elastic layer on a cored bar. As the elastic layer material, for example, a specific resistivity of 10 ⁵
Ωcm chloroprene rubber is used. The roller 65 is configured to apply a voltage having a positive polarity opposite to the normal polarity of the toner from a power supply 65a for suction. The transfer paper that has passed between the electrostatic attraction roller 65 and the entrance roller 61 in a state where a voltage is applied from the power supply 65 a for adsorption is electrostatically attracted onto the transfer / conveying belt 60.

Further, as a transfer electric field forming means for forming a transfer electric field at each transfer nip portion, a transfer conveying belt 6 which forms a transfer nip portion in contact with and opposed to the photosensitive drum.
0 so that the transfer bias applying member 67
Y, 67M, 67C and 67K are provided. The transfer bias applying members 67Y, 67M, 67C, and 67K are fixed brushes made of a conductive mylar, and transfer biases are applied from transfer bias power sources 9Y, 9M, 9C, and 9K. By the transfer bias applied by the transfer bias applying member, a transfer charge is applied to the transfer conveyance belt 60,
At each transfer nip, a transfer electric field having a predetermined intensity is formed between the transfer conveyance belt 60 and the surface of the photosensitive drum.

Each of the photosensitive drums 11Y, 11M, 1M
Backup rollers 68Y and 68 pressing the transfer conveyance belt 60 toward the photosensitive drum corresponding to 1C and 11K.
M, 68C and 68K are provided. Each of the backup rollers 68Y, 68M, 68C, and 68K partially winds the transfer conveyance belt 60 around the peripheral surface of the photosensitive drum 11Y on the upstream side in the transfer paper moving direction of each transfer nip portion. Thereby, the contact pressure between the transfer paper P and each of the photosensitive drums at the transfer nip is increased, and the transfer efficiency at the transfer nip is increased.

The stretched portion between the support rollers 63 and 64 of the transfer / transport belt 60 on the side where the transfer sheet is not transported is
A cleaning roller 66 as a cleaning member for cleaning toner adhered to the surface of the transfer conveyance belt 60 and an opposing roller 69 facing the cleaning roller 66 via the transfer conveyance belt 60 are arranged.
In this example, the cleaning roller 66 is formed of a conductive metal roller, and the opposing roller 73 is formed of a sponge roller having an elastic foam layer made of a conductive sponge material on a cored roller. . When a bias having a polarity opposite to the normal charging polarity of the toner is applied to the cleaning roller 66 from the cleaning bias power source 66a, the toner is cleaned at the cleaning nip portion where the transfer conveyance belt 60 and the cleaning roller 66 come into contact with each other. A cleaning electric field that moves toward the roller 66 is formed. With this electric field, the transfer conveyance belt 6
The toner adhering to the transfer belt 60 is moved to the cleaning roller 71 side, and the toner is removed from the surface of the transfer conveyance belt 60.
The toner that has moved to the cleaning roller 71 is scraped off by the cleaning blade 72 and removed from the surface of the roller 71.

In the transfer unit 6 of the present embodiment, a support roller 62 (hereinafter, referred to as a drive roller) that applies the maximum driving force to the transfer / transport belt 60 among the four support rollers that support the transfer / transport belt 60. Is disposed downstream of the transfer nip portion in contact with and facing the photoconductor 11 </ b> K in the surface movement direction of the transfer conveyance belt 60. The drive roller 62 is driven by a drive source (not shown), and frictionally drives the transfer conveyance belt 60. Further, specifically, the linear speed of the transfer conveyance belt 60 is changed so that there is a relative speed difference between the linear speed of the transfer conveyance belt 60 and the linear speed of the cleaning roller 66. It is configured to be larger than. In the present embodiment, as shown in FIG.
Is rotated so that the surface moves in the forward direction with respect to the surface moving direction of the transfer conveyance belt 60, but may be rotated in the reverse direction.

In the transfer unit 6 having the above structure, the linear speed of the transfer belt 60 is set to be higher than the linear speed of the cleaning roller 66. Act as That is, in the cleaning section that performs the cleaning, the rotation of the cleaning roller 66 generates a force that tries to stop the traveling of the transfer conveyance belt 60. This force is applied to the transfer conveyance belt 6 more than the cleaning unit.
It acts as a force to pull the belt on the downstream side in the surface movement direction 0 in the direction opposite to the belt surface movement direction. Therefore, a tension in a direction opposite to the belt surface moving direction is generated on the transfer conveyance belt 60 between the cleaning unit including the transfer nips and the driving roller 62. The same applies to the case where the rotation direction of the cleaning roller 66 is set to be opposite to the direction in which the surface of the transfer conveyance belt 60 moves.

Due to the above-mentioned tension, the transfer paper conveyance area of the transfer conveyance belt 60 is less likely to be slackened than other parts, and is always maintained in a tensioned state. In the transfer unit 6 of the present embodiment, since the transfer paper P is transported in the transfer paper transport area maintained in the stretched state, the transfer paper P is not easily affected by the supply and separation of the transfer paper P to the transfer transport belt 60.
Thereby, the transfer conveyance belt 60 accompanying the supply and separation is provided.
Can be reduced, and the speed unevenness of the transfer conveyance belt 60 can be suppressed. Therefore, pitch unevenness and color shift on the image due to the speed unevenness can be suppressed, and the image quality can be improved.

In the transfer unit 6 having the above-described structure, the transfer / conveyance belt 60 at the cleaning nip portion is provided.
The shearing force is applied to the toner between the transfer conveyance belt 60 and the cleaning roller 66 due to the relative speed difference between the linear speed of the cleaning roller 66 and the linear speed of the cleaning roller 66. Due to this shearing force, a part of the toner adhered to the surface of the transfer conveyance belt 60 is mechanically peeled off, and the charged toner adhered to the surface of the transfer conveyance belt 60 can be easily cleaned by the cleaning electric field. . Therefore, the cleaning performance of the transfer conveyance belt 60 can be improved.

FIG. 4 is a graph showing the relationship between the linear velocity difference between the transfer conveyance belt 60 and the cleaning roller 66 and the cleaning performance of the transfer conveyance bell 60. The vertical axis indicates the cleaning performance, and the horizontal axis indicates the linear velocity difference (%) based on the linear velocity of the transfer conveyance belt 60. FIG. 4 shows that when the linear velocity difference is ± 2% or more, the cleaning performance tends to be improved due to an increase in the shearing force. That is, the cleaning performance of the transfer conveyance belt 6
Regardless of the magnitude relationship between the linear velocity of 0 and the linear velocity of the cleaning roller 66, it is good if the linear velocity difference is equal to or larger than a predetermined range. On the other hand, FIG. 5 is a graph showing a relationship between a linear velocity difference between the transfer conveyance belt 60 and the cleaning roller 66 and an average color shift amount of an output image. The vertical axis indicates the average color shift amount, and the horizontal axis indicates the linear velocity difference (%) based on the linear velocity of the transfer conveyance belt 60. From FIG. 5, when the linear velocity difference (%) is in a negative range, that is, when the linear velocity of the transfer transport belt 60 is set to be higher than the linear velocity of the cleaning roller 66, the transfer transport belt 6
It can be confirmed that the transfer paper transport area of 0 can be maintained in a stretched state, and the amount of color misregistration is reduced. From the graphs of FIGS. 4 and 5, in order to achieve both improvement in image quality and improvement in cleaning performance in the present embodiment, the linear speed of the cleaning roller 66 is set to 98% or less of the linear speed of the transfer conveyance belt 60. It is preferable to set so that

In the transfer unit 6 having the above structure, the linear velocity of each photosensitive drum 11 and the transfer / conveyance belt 60
If the linear velocity of each photoconductor drum 11 at each transfer nip portion becomes smaller than the linear velocity of the transfer conveyance belt 60 due to some influence, as shown in FIG. Therefore, the transfer / conveying belt 60 may be loosened. Therefore, in the present embodiment, the linear velocity of each photoconductor drum 11 in each transfer nip portion is determined by the transfer conveyance belt 6.
It is preferable to set the linear velocity so as to be higher than zero. By setting as described above, the transfer conveyance belt 6
Since the slack of zero can be suppressed, the transfer paper conveyance area of the transfer conveyance belt 60 can be always maintained in a stretched state.

Incidentally, in order to suppress the slack of the transfer conveyance belt 60 as shown in FIG. 7, the linear speed of each photosensitive drum 11 is set to be higher than the linear speed of the transfer conveyance belt 60. You can also. In this case, the linear velocity difference between the cleaning roller 66 and the transfer conveyor belt 60 is set to be larger than the linear velocity difference between each photosensitive drum 11 and the transfer conveyor belt 60. In such a setting, the photoconductor 11K
Transfer convection belt 60 than the transfer nip portion in contact with and facing
The tension in the direction opposite to the belt surface movement direction acting on the transfer conveyance belt 60 between the cleaning unit and the transfer nip portion on the upstream side in the surface movement direction becomes larger than the force for pushing out the transfer conveyance belt 60. Therefore, it is possible to suppress the slack of the transfer conveyance belt 60 as shown in FIG. 7, and to maintain the transfer conveyance region of the transfer conveyance belt 60 always in a stretched state.

[Embodiment 2] FIG. 6 is a schematic structural view of a transfer unit 6 of a laser printer according to another embodiment of the present invention. In the present embodiment, the transfer conveyance belt 60
The driving roller that gives the maximum driving force to the photosensitive member 11Y
Transfer belt 60 than the transfer nip portion in contact with and facing
Embodiment 1 in that it is arranged on the upstream side in the surface movement direction of
Unlike the configuration of the laser printer (see FIGS. 1 to 3),
The other configurations are almost the same, and the description thereof is omitted. Also, the basic image forming operation of the laser printer is the same as that of the laser printer of the first embodiment, and the description thereof will be omitted.

In this embodiment, a support roller 61 (hereinafter, referred to as a drive roller) as a drive roller is disposed downstream of the transfer nip portion in contact with the photosensitive member 11Y in the surface movement direction of the transfer / transport belt 60. ing. Further, the linear velocity of the cleaning roller 66 is configured to be higher than the linear velocity of the transfer conveyance belt 60.

In the transfer unit 6 having the above configuration, the linear speed of the cleaning roller is set to be higher than the linear speed of the transfer / conveyance belt 60. A force for pushing the transfer conveyance belt 60 in the surface movement direction of the transfer conveyance belt 60 is generated. This force acts as a force that pulls the belt on the upstream side in the surface movement direction of the transfer conveyance belt 60 from the cleaning unit in the belt surface movement direction. Therefore, a tension in the belt surface moving direction is generated on the transfer conveyance belt 60 between the drive roller 61 including each transfer nip and the cleaning nip.

Due to the above-mentioned tension, the transfer paper conveyance area of the transfer conveyance belt 60 is less likely to be slackened than other parts, and is always maintained in a tensioned state. Therefore, as in the first embodiment, the speed unevenness of the transfer conveyance belt 60 can be suppressed, so that pitch unevenness and color shift on the image due to the speed unevenness can be suppressed, and the image quality is improved. be able to. Further, the cleaning performance of the transfer conveyance belt 60 can be improved.

Here, the linear speed of each photoconductor drum 11 and the linear speed of the transfer / conveyance belt 60 are set to be equal, and the linear speed of each photoconductor drum 11 at each transfer nip portion is set to the same speed. When the speed becomes higher than the linear velocity, a force for pushing out the transfer conveyance belt 60 is generated in the surface movement direction of the transfer conveyance belt 60, and as shown in FIG.
0 may be loosened. Therefore, in the present embodiment, the transfer conveyance belt 60 in each transfer nip portion is used.
Is set to be higher than the linear speed of each photosensitive drum 11. By setting like this,
Since the slack of the transfer conveyance belt 60 can be suppressed, the transfer paper conveyance region of the transfer conveyance belt 60 can be always maintained in a stretched state.

In order to suppress the slack of the transfer belt 60 as shown in FIG. 8, the linear speed of the transfer belt 60 is set to be higher than the linear speed of each photosensitive drum 11. You can also. In this case, the linear velocity difference between the cleaning roller 66 and the transfer conveyor belt 60 is set to be larger than the linear velocity difference between each photosensitive drum 11 and the transfer conveyor belt 60. In such a setting, the photoconductor 11K
Transfer convection belt 60 than the transfer nip portion in contact with and facing
The transfer nip and the drive roller 6 are moved by the tension in the belt surface movement direction acting on the transfer conveyance belt 60 between the cleaning unit and the transfer nip unit on the downstream side in the surface movement direction of the transfer roller 6.
1, the transfer / conveying belt 60 is less likely to be slackened. Therefore, the slack of the transfer conveyance belt 60 as shown in FIG. 8 can be suppressed, and the transfer conveyance area of the transfer conveyance belt 60 can be always maintained in a stretched state.

In each of the above embodiments, the present invention is applied to a laser printer having four sets of toner image forming units for forming images of four colors of yellow, magenta, cyan, and black. The present invention can be applied without being limited to the number of toner image forming units, and the same effects can be obtained. In each of the above embodiments, the present invention is applied to a laser printer that transfers a toner image on a photosensitive drum to transfer paper carried on a transfer / conveying belt.
The present invention can also be applied to a laser printer that transfers a toner image on a so-called intermediate transfer member onto transfer paper on a transfer / conveyance belt. Further, the present invention is not limited to a laser printer, but can be applied to other image forming apparatuses such as a copying machine.

[0067]

According to the first to fifteenth aspects of the present invention, there is an excellent effect that the unevenness of the speed of the transfer conveyance belt can be suppressed and the cleaning performance of the transfer conveyance belt can be improved.

In particular, according to the first to twelfth aspects of the invention,
There is an excellent effect that pitch unevenness on an image due to speed unevenness of the transfer conveyance belt can be suppressed and image quality can be improved.

In particular, according to the second, eleventh and fourteenth aspects of the present invention, the supporting roller for applying the maximum driving force to the transfer / conveying belt is located downstream of the transfer nip in the surface moving direction of the transfer / conveying belt. In the case where the transfer conveyance belt is disposed, the transfer conveyance belt between the cleaning section including the transfer nip portion and the support roller that applies the maximum driving force to the transfer conveyance belt can be always maintained in a stretched state, and the transfer conveyance belt There is an excellent effect that speed unevenness can be suppressed.

In particular, according to the third and fourth aspects of the present invention, the support roller for applying the maximum driving force to the transfer / transport belt is disposed downstream of the transfer nip in the surface movement direction of the transfer / transport belt. In this case, the transfer conveyance belt between the transfer nip portion and the support roller that applies the maximum driving force can be constantly maintained in a stretched state, and the speed unevenness of the transfer conveyance belt can be suppressed. There is an excellent effect.

In particular, according to the fifth, twelfth and fifteenth aspects of the present invention, the supporting roller for applying the maximum driving force to the transfer / conveying belt is located upstream of the transfer nip in the surface moving direction of the transfer / conveying belt. When the transfer conveyance belt is disposed, the transfer conveyance belt between the cleaning unit including the transfer nip portion and the support roller that applies the maximum driving force to the transfer conveyance belt can be always maintained in a stretched state, and the speed of the transfer conveyance belt can be maintained. There is an excellent effect that unevenness can be suppressed.

In particular, according to the inventions of claims 6 and 7, the support roller for applying the maximum driving force to the transfer / conveying belt is disposed upstream of the transfer nip in the surface moving direction of the transfer / conveying belt. In such a case, the transfer conveyance belt between the support roller that applies the maximum driving force and the transfer unit can be maintained in a stretched state at all times, and the speed unevenness of the transfer conveyance belt can be suppressed. Has an effect.

In particular, according to the invention of claim 8, it is possible to generate a sufficient tension on the transfer / conveying belt and to apply a sufficient shearing force to the toner adhered to the surface of the transfer / conveying belt. Has an excellent effect.

In particular, according to the ninth aspect of the invention, there is an excellent effect that a high quality image without color shift can be obtained in a color image in which toner images of respective colors are superimposed on a transfer material.

[Brief description of the drawings]

FIG. 1 is a schematic configuration diagram of a transfer unit of a laser printer according to a first embodiment.

FIG. 2 is a schematic configuration diagram of the laser printer.

FIG. 3 is an enlarged view showing a schematic configuration of a toner image forming unit of the laser printer.

FIG. 4 is a graph showing a relationship between a linear velocity difference between a transfer conveyance belt and a cleaning roller and a cleaning performance of the transfer conveyance belt.

FIG. 5 is a graph illustrating a relationship between a linear velocity difference between a transfer conveyance belt and a cleaning roller and an average color shift amount of an output image.

FIG. 6 is a schematic configuration diagram of a transfer unit of the laser printer according to the second embodiment.

FIG. 7 is an explanatory diagram for explaining a problem of a transfer unit according to a comparative example.

FIG. 8 is an explanatory diagram for explaining a problem of a transfer unit according to another comparative example.

FIG. 9 is a schematic configuration diagram illustrating an example of a conventional image forming apparatus.

[Explanation of symbols]

 REFERENCE SIGNS LIST 1 toner image forming unit 5 registration roller pair 6 transfer unit (transfer device) 7 fixing unit 9 transfer bias power supply 10 photoconductor unit 11 photoconductor drum 20 developing unit 60 transfer conveyor belt 61-64 support roller 65 electrostatic attraction roller 66 cleaning Roller 69 Opposing roller

 ────────────────────────────────────────────────── ─── Continued on the front page (72) Inventor Kazuhiko Kobayashi 1-3-6 Nakamagome, Ota-ku, Tokyo F-term in Ricoh Co., Ltd. (Reference) 2H027 ED02 ED24 EE03 EF09 EG06 2H030 AB02 AD03 BB44 BB53 2H032 AA05 AA15 BA01 BA18 BA23 BA30 CA02

Claims (15)

[Claims] An image carrier on which a toner image composed of a charged toner having a predetermined polarity is formed; and a transfer nip portion whose surface moves along an endless path including a transfer nip portion in contact with and opposed to the image carrier. A transfer conveyance belt for carrying the transfer material on the transfer conveyance belt, a cleaning member for cleaning the surface of the transfer conveyance belt at a cleaning nip portion in contact with and facing the surface of the transfer conveyance belt, and the cleaning nip portion having the predetermined polarity. A cleaning electric field forming means for forming a cleaning electric field for moving the charged toner to the cleaning member side, wherein a linear velocity of the transfer conveyance belt and a line of the cleaning member in the cleaning nip portion are provided. An image forming apparatus having a relative speed difference with respect to the speed. 2. The image forming apparatus according to claim 1, wherein, of the plurality of support rollers for supporting the transfer / conveying belt, a supporting roller for applying a maximum driving force to the transfer / conveying belt is more than the transfer nip portion. The cleaning member is disposed on the downstream side in the surface movement direction of the transfer conveyance belt, and the cleaning member is disposed further downstream than the support roller that applies the maximum driving force. An image forming apparatus which is set so as to be higher than a linear velocity of a member for use. 3. The image forming apparatus according to claim 2, wherein the linear speed of the transfer conveyance belt in the transfer section is set to be higher than the linear speed of the image carrier. . 4. The image forming apparatus according to claim 2, wherein a linear speed of the image carrier in the transfer nip portion is set to be higher than a linear speed of the transfer conveyance belt.
The image forming apparatus is characterized in that a relative speed difference between the cleaning member and the transfer conveyance belt is set to be larger than a relative speed difference between the image carrier and the transfer conveyance belt. 5. The image forming apparatus according to claim 1, wherein, among the plurality of support rollers for supporting the transfer / conveyance belt, a support roller for applying a maximum driving force to the transfer / conveyance belt is more than the transfer nip portion. The cleaning member is disposed on the upstream side in the surface movement direction of the transfer conveyance belt, and the cleaning member is further disposed on the upstream side of the support roller that applies the maximum driving force. An image forming apparatus characterized in that it is set to be higher than the linear velocity of a conveyor belt. 6. The image forming apparatus according to claim 5, wherein a linear speed of the image carrier in the transfer nip portion is set to be higher than a linear speed of the transfer conveyance belt. apparatus. 7. The image forming apparatus according to claim 5, wherein the linear speed of the transfer conveyance belt at the transfer nip is set to be higher than the linear speed of the image carrier, and the cleaning member and An image forming apparatus, wherein a relative speed difference between the transfer conveyance belt and the image carrier is set to be larger than a relative speed difference between the image carrier and the transfer conveyance belt. 8. The image forming apparatus according to claim 1, wherein the linear velocity of the cleaning member is 98% or less or 102% or more of the linear velocity of the transfer conveyance belt. Image forming apparatus. 9. An image forming apparatus according to claim 1, wherein a plurality of said image carriers are provided, and said plurality of image carriers form toner images of mutually different colors, respectively.
A color image is formed by moving the transfer conveyance belt along an endless path including a plurality of transfer nip portions facing each of the plurality of image carriers, and superimposing and transferring each toner image onto a transfer material. An image forming apparatus comprising: 10. A step of forming a toner image composed of charged toner having a predetermined polarity on an image carrier, and a transfer conveyance belt moving on a surface along an endless path including a transfer nip portion in contact with and facing the image carrier. A step of transferring the toner image on the image carrier to the transfer material by supporting and transferring the transfer material; and a step of transferring the toner having the predetermined polarity to the cleaning section where the transfer / transport belt and the cleaning member come into contact with each other. Forming a cleaning electric field for moving the transfer conveying belt to the cleaning member side, and performing a cleaning step of cleaning the transfer conveying belt after the transfer. An image forming method, wherein a relative speed difference between the linear speed of the member and the linear speed of the member is provided. 11. The cleaning nip according to claim 10, wherein, of the plurality of support rollers for supporting the transfer conveyance belt, the cleaning nip is located downstream of the transfer nip in the surface movement direction of the transfer conveyance belt. A maximum driving force is applied to the transfer conveyance belt by a support roller provided on the upstream side of the transfer conveyance belt in the surface movement direction of the transfer conveyance belt, and the linear speed of the transfer conveyance belt is reduced by the linear speed of the cleaning member. An image forming method characterized in that the size of the image is larger than that of the image. 12. The cleaning nip according to claim 10, wherein, of the plurality of support rollers for supporting the transfer conveyance belt, the cleaning nip is located on the upstream side in the surface movement direction of the transfer conveyance belt from the transfer nip portion. A support roller provided on the downstream side of the transfer unit, applying a maximum driving force to the transfer / transport belt, and making the linear velocity of the cleaning member greater than the linear velocity of the transfer / transport belt. Image forming method. 13. A transfer conveyance belt whose surface moves along an endless path including a transfer nip portion which is in contact with and opposes an image carrier, and which carries and transfers a transfer material to the transfer nip portion; A cleaning member that cleans the surface of the transfer conveyance belt at a cleaning nip portion that is in contact with and opposed to the surface; and a cleaning that forms a cleaning electric field that moves the charged toner having the predetermined polarity to the cleaning member side at the cleaning nip portion. A transfer device provided with a cleaning electric field, wherein a linear speed of the transfer conveying belt and a linear speed of a cleaning member in the cleaning nip portion are different from each other. 14. The transfer device according to claim 13, wherein, among the plurality of support rollers for supporting the transfer / conveyance belt, a support roller for applying a maximum driving force to the transfer / conveyance belt is more than the transfer nip portion. The cleaning member is disposed further downstream than the support roller that applies the maximum driving force, while the cleaning member is disposed further downstream than the transport belt in the surface movement direction. A transfer device, wherein the transfer speed is set to be higher than the linear velocity of the member. 15. The transfer device according to claim 13, wherein, of the plurality of support rollers for supporting the transfer / conveyance belt, a support roller for applying a maximum driving force to the transfer / conveyance belt is more than the transfer nip portion. The cleaning member is disposed on the upstream side in the surface movement direction of the conveyor belt, and the cleaning member is further disposed on the upstream side of the support roller that applies the maximum driving force. A transfer device characterized in that the transfer speed is set to be higher than the linear velocity of the belt.